Study On The Changes Of Storage Quality Of Ningxia Cabbage After Harvest

The leaves of cabbage in Ningxia have high water content,large surface area,crisp and tender tissue.They are easy to be affected by field heat,transpiration and respiration.The leaves are easy to cause mechanical damage,water loss,rapid decline in commercial value and nutritional quality,and serious food safety problems,especially in the arid and rainless Ningxia area It is easy to cause quality deterioration and other problems.Precooling is the key link of post harvest treatment of fruits and vegetables.Through precooling,the field heat brought by fruits and vegetables can be quickly eliminated,so as to achieve the purpose of cooling.Low temperature storage refers to the method of storage of fruits and vegetables under suitable low temperature environment,which can effectively maintain the quality of fruits and vegetables and prevent the reduction of their edible value.In order to maintain the freshness and good sensory quality of Ningxia cabbage and prolong its shelf life,it is very important to precool and low temperature storage after harvesting.The quality indexes and sensory evaluation of Ningxia cabbage heart are taken as the evaluation criteria.The vacuum precooling technology and cold storage precooling technology are used to pretreat the collected Ningxia cabbage heart,and the quality change rule of Ningxia cabbage heart stored at low temperature is studied.Through analysis and comparison,the best Precooling method and storage conditions are selected.On this basis,according to the relevant quality indicators,the shelf life prediction model of Ningxia cabbage was established.(1)The effect of precooling and low temperature on the quality of Ningxia cabbage during postharvest storage.The experiments of vacuum precooling,cold storage precooling and low temperature storage were carried out at the final precooling temperature of 0,5,10?,respectively.The weight loss rate,chlorophyll content,color,respiratory intensity,soluble solids,peroxidase and polyphenol oxidase were analyzed The quality index of malondialdehyde and the change rule of sensory evaluation were used to determine the best precooling method and storage conditions.Under the condition of 0,5,10?,the variation of the cooling rate of the center temperature and the skin temperature of Ningxia cabbage,the variation of the pressure of vacuum precooling were studied.(2)Establishment of shelf life prediction model of Ningxia cabbageThe fresh-keeping effect of vacuum precooling is better than that of cold storage precooling.Therefore,vacuum precooling is the precondition of precooling,and the quality indexes of weight loss rate,chlorophyll content,color measured in the storage period are taken as the key factors,and these quality indexes are used for dynamic analysis,The shelf life is predicted.Therefore,based on the study of weight loss rate,chlorophyll content and color(L*,a*,b*)hanges of Ningxia cabbage during the storage period under different storage temperatures(273k,278k,283k),the shelf-life model of Ningxia cabbage was predicted by dynamic quality function and Arrhenius equation.